1. Field of the Invention
The present invention relates to an apparatus for automatically measuring electric characteristics of chip electronic components each having electrodes on both end surfaces.
2. Description of the Background Art
Chip electronic components such as chip capacitors, chip resistors and the like are widely used due to advantages such as miniaturization, increase in mounting density, high reliability, suitability for automatic mounting, and the like. In order to mount such chip electronic components on substrates, it is necessary to previously measure electric characteristics thereof for the purpose of quality inspection. FIG. 11 shows a conventional characteristic measuring apparatus.
Referring to FIG. 11, a turn table 50 is provided with a large number of stepped holding holes 52 at constant pitches for holding chip electronic components 51, while fixed terminals 53 and movable terminals 54 are arranged closely on both sides of the turn table 50. The fixed and movable terminals 53 and 54 are provided in plural respectively at the same pitches as the holding holes 52 of the turn table 50. The movable terminals 54 are formed of pin terminals slidably supported by a slider 55, which is movable along a direction for being close to and separated from the turn table 50, and urged by springs 56 to project toward the turn table 50. The movable terminals 54 are provided on first end portions thereof with small-diameter shaft portions 54a, which can be inserted in small-diameter portions 52a of the holding holes 52 provided in the turn table 50. The second end portions of the movable terminals 54 are connected with measuring devices (not shown) through wires 57, while the fixed terminals 53 are also connected with the measuring devices.
In order to measure the characteristics of each chip electronic component 51, the slider 55 is leftwardly moved in FIG. 11 to insert the shaft portion 54a of the movable terminal 54 in the holding hole 52, thereby bringing the same into pressure contact with an end surface of the chip electronic component 51. The movable terminal 54 presses the chip electronic component 51 to bring the other end surface thereof into contact with the fixed terminal 53, thereby electrically connecting the chip electronic component 51 with the measuring devices for measuring the characteristics. When measurement of the characteristics is completed, the slider 55 is rightwardly moved in FIG. 11 to separate the movable terminal 54 from the chip electronic component 51, while the turn table 50 is rotated along the arrow by one pitch to measure the characteristics of the next chip electronic component through an operation similar to the above.
In the aforementioned characteristic measuring apparatus, it is necessary to mount components such as the springs 56 on the movable terminals 54, which are formed of pin terminals. Thus, the number of components is increased which will inevitably widen the terminal-to-terminal pitch P. Particularly when a large number of movable terminals 54 are arcuately arranged in order to simultaneously measure the characteristics of a large number of chip electronic components 51, the number of simultaneously measurable chip electronic components 51 is restricted and this reduces the measuring capability of the apparatus. Further, the holding holes 52 must be stepped to prevent falling of the chip electronic components 51 upon separation from the movable terminals 54, while the movable terminals 54 must be provided with the shaft portions 54a which are inserted in the small-diameter portions 52a of the holding holes 52. In particular, such holding holes 52 and small-diameter portions 52a are reduced in size with miniaturization of the chip electronic components 51, to cause difficulty in the machine work for obtaining the shaft portions 54a. The shaft portions 54a may damage the chip electronic components 51 since the same are brought into pressure contact with the end surfaces of the chip electronic components 51 in small areas. Further, the movable terminals 54 require excessively long strokes for passing through the small-diameter portions 52a of the holding holes 52, and this retards the speed of measurement.